Thumbs for excavators are well known (the term “excavator” as used herein is intended to encompass excavators, backhoes, and other machines having an arm or “dipper stick” that carries a bucket or other work implement). These thumbs are secured to the arm of the excavator and are arranged relative to the bucket or other work implement so as to provide an opposable member to aid in grasping large or odd-shaped objects and/or for other purposes. The thumb includes a body having an inner end secured to the excavator arm and an outer end that is spaced outwardly from the arm. The outer end can have any of a wide variety of shapes and sizes, depending upon the work being performed, e.g., carrying logs, carrying demolition debris, lifting large rocks or metal plates, etc. These thumbs can be fixed, manually adjustable, or hydraulically adjustable.
U.S. Pat. No. 6,655,053 and U.S. Pat. No. 5,678,332 disclose excavator thumbs that include removable outer ends or implements that are selected and installed depending upon the type of work to be performed. The implements are telescopically installed on the inner portion of the thumb.
U.S. Pat. No. 7,240,441 discloses a thumb that is telescopically extendible and retractable as needed.
U.S. Pat. No. 5,553,408 discloses a thumb/claw for an excavator in which a mounting box is secured adjacent the excavator bucket, and either multiple clamping teeth or a single ripping tooth is/are operatively secured to the mounting box as needed.
U.S. Patent Application Publication No. 2010/0058622 discloses a thumb and a mounting structure for selectively and releasably connecting a tooth bar to the thumb.
U.S. Patent Application Publication No. 2002/0101107 discloses a thumb assembly that includes differently sized clamping assemblies that can be installed depending upon the type of work to be performed.
None of these prior thumbs have been found to provide a desired convenient and effective structure for selectively changing the outer working portion of the thumb as needed while also providing the required strength in a cost-effective and lightweight structure that is easy to use.